LASIK术中瞬时高眼压对兔视网膜组织NO含量及NOS活性的影响

摘要

目的：观察准分子激光原位角膜磨镶术( LASIK)术中不同持续时间的负压吸引引起的瞬时高眼压对视网膜组织NO含量及一氧化氮合酶( NOS)活性的影响,探讨LASIK术中负压吸引安全时间。方法将实验用68只新西兰大耳白兔随机分为五组。负压吸引20 s组(n=20)、负压吸引45 s组(n=20)和负压吸引3 min组(n=20)模拟LASIK手术过程,负压吸引时间分别持续20 s、45 s及3 min；实验对照组(n=4)仅行单眼原位角膜激光消融,正常对照组(n=4)不进行任何处理。各负压吸引组分别于术后即刻、7天、10天、14天、28天各处死动物4只,实验对照组于激光消融后处死动物,同时处死正常对照组动物。采用752型分光光度计测各组视网膜组织NO含量及NOS活性。结果 NO含量及NOS活性：实验对照组与正常对照组比较差异均无统计学意义(P均>0.05)；负压吸引20 s组、45 s组术后各时点与正常对照组比较差异均无统计学意义(P均>0.05)。负压吸引3 min组术后即刻与正常对照组比较差异均无统计学意义(P均>0.05),术后7天、10天高于正常对照组(P均<0.05),术后14天、28天与正常对照组比较差异无统计学意义(P均>0.05)；术后7天NO含量及NOS活性达高峰,二者表达呈正相关(r=0.982,P<0.05)。结论 LASIK术中常规负压吸引20 s、45 s不会导致视网膜组织NO含量及NOS活性改变；负压吸引时间延长至3 min可引起视网膜组织NO含量及NOS活性升高,但这种改变是可逆性的,术后修复28天基本恢复正常。%Objective To observe the effects of transient high intraocular pressure ( IOP) caused by negative pressure suction at different time of duration during laser-assisted in situ keratomileusis ( LASIK) on the changes of NO and NOS in retinal tissues and to investigate the safe time of negative pressure suction during LASIK. Methods Sixteen-eight New Zealand white rabbits were randomly divided into the normal control group ( n=4 ) , the experimental control group ( n=4), 20 s suction group (n=20), 45 s suction group (n=20) and 3 min suction group (n=20), whose time of negative pressure suction was respectively 20 s, 45 s and 3 min. LASIK surgical procedure was simulated, and the experimental control group only received laser ablation and the normal control group without any treatment. The animals in the suction groups were executed immediately (0 d), after 7 d, 10 d, 14 d and 28 d. The rabbits in the experimental control group were executed after laser ablation. Meanwhile, the rabbits in the normal control group were executed. The NO content and NOS activity in retinal tissue of each group were detected by 752 spectrophotometer. Results NO content and NOS activi-ty:no significant difference was found between the normal control group and the experimental control group ( all P >0. 05), no significant difference was found at every postoperative time between the 20 s suction group, 45 s suction group and normal control group (all P>0. 05), no statistically significant difference was found between the 3 min suction group and the normal control group immediately after operation (all P>0. 05). Seven days and 10 day after operation, the NO content and NOS activity in the 3 min suction group were higher than those of the normal control group (all P<0. 05). No significant difference in the NO content and NOS activity was found between the 3 min suction group and the normal control group 14 days and 28 days after operation (all P>0. 05). The NO content and NOS activity reached a peak 7 d after oper-ation, and they were positively correlated with each other (r=0. 982, P<0. 05). Conclusions Conventional suction of 20 s and 45 s in LASIK does not cause the change of NO content and NOS activity in the retinal tissues. When the suction time extends to 3 min, the NO content and NOS activity, but this change is reversible increase, after 28-day restoration, it can return to normal.